@tommyboy180:
What game is this, is I may ask?
He says it was Guilty Gear.
Update. My son has this working to some extent and is able to play the game against an on-line opponent. It may be that he just wasn't familiar with the game and needed to select an 'active' session to connect to. Can't say for sure as he mucked around in my pfSense while I was at work.
Hard to say as when I do the GRC ShieldsUp test it shows it as Stealth right now.
I don't do gaming or on-line sessions of this type so don't understand what's needed.
Thanks to all for your help.